Method and apparatus for controlled gene or protein delivery

ABSTRACT

An implantable system which includes a gene/protein delivery device and a pulse generator, as well as method of preparing the gene/protein delivery device and using the system, are provided. In one embodiment, the implantable system detects a predetermined condition or event and, in response, delivers gene(s) and/or protein(s) in conjunction with delivering pacing and/or defibrillation pulses.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to, commonly assigned U.S. patentapplication Ser. No. 10/862,716, entitled “METHOD AND APPARATUS TOMODULATE CELLULAR REGENERATION POST MYOCARDIAL INFARCT,” filed on Jun.7, 2004 and U.S. patent application Ser. No. 10/788,906, entitled“METHOD AND APPARATUS FOR DEVICE CONTROLLED GENE EXPRESSION,” filed onFeb. 27, 2004, which are hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

This invention relates generally to gene therapy of living tissue andparticularly, but not by way of limitation, to method and apparatus fordelivering gene or protein using an implantable medical device.

BACKGROUND OF THE INVENTION

Many techniques currently exist for delivering drugs or othermedicaments to body tissue. These include topical or transcutaneousadministration where the drug is passively absorbed, or caused to pass,into or across the skin or other surface tissue; oral administration;injection directly into body tissue such as through an intramuscularinjection or the like; and intravenous administration, which involvesintroducing a selected drug directly into the blood stream.Transcutaneous drug delivery systems are usually limited to externaladministration of a drug through the patient's skin or other surfacetissue, and thus is inefficient because some of the drug may be absorbedby healthy tissue before it reaches the diseased or damaged area, orcarried beyond the diseased or damaged area. Oral administration,injection, and intravenous administration are systemic and so fail toconcentrate the drug in a local area.

Transportation of a drug using a localized drug delivery system may beenhanced through means such as iontophoresis. Iontophoresis typicallyinvolves an interaction between ionized molecules of a drug and anexternal electric field, which results in the migration of chargedmolecules. The migration is accomplished by placing two electrodesacross the tissue to be treated and charging the electrodes with arelatively low, direct current (DC), voltage. One of the electrodes actsas a source electrode and is typically in contact with the drugsolution. The other electrode acts as a return electrode and may befilled with an electrolyte solution. The electric field generatedbetween the two electrodes causes the charged molecules to migrate fromone electrode into the tissues to be treated.

Nevertheless, problems are associated with introducing an electricalcurrent into the body, including muscle stimulation and contraction, aswell as pain or other unwanted sensations. More importantly, the problemof cardiac arrhythmia (irregular rhythm) can easily arise whenelectrical current passes through the heart. The current source causingthat problem can originate from an external source, within the heartitself, or adjacent to the heart, such as from a coronary artery.

Intensity (current density), frequency, waveform and duration of theelectrical current used in iontophoresis have an effect on whethercardiac arrhythmias and other problems will occur, as well as themagnitude of those reactions. The threshold at which ventricularfibrillation occurs with various transthoracic and intracardiacelectrical levels increases with higher frequency currents. Thethreshold of sensation also increases with higher frequencies. Forinstance, U.S. Pat. No. 5,087,243 discloses a method which attempts tominimize the risk of iontophoresis-induced arrhythmias. An implantedmyocardial iontophoresis patch system is disclosed therein which apulsed current is supplied to the anodal patch. Electrical activity inthe patient's heart is monitored and the iontophoresis current is pulsedon and off in synchronization with ventricular depolarization to avoidthe interval during which the heart is vulnerable to electricallyinduced arrhythmias or unnatural heart rhythms.

What is needed is an improved apparatus for local, transient delivery ofgene(s) and/or protein(s), e.g., one which is employed in conjunctionwith electrical therapy.

SUMMARY OF THE INVENTION

The present invention is directed to the local, transient delivery of atherapeutic agent, such as a nucleic acid molecule (polynucleotide) orprotein, from a polymer matrix to the myocardium, a vessel, or any otherorgan or area for which transluminal access is desirable of a mammalhaving or at risk of a particular condition. For example, the presentinvention can be used to locally administer via iontophoresis isolatednucleic acid or protein to the myocardium of a mammal having or at riskof a cardiovascular condition in response to detection of a parameter ora change in a parameter which is associated with the condition, e.g.,the isolated nucleic acid and/or protein is administered in an amounteffective to transiently alter, e.g., enhance, myocardial function.Iontophoresis technology uses an electrical potential or current acrossa permeable barrier to drive ionic molecules such as nucleic acid orprotein, or drag nonionic molecules in an ionic solution. Iontophoresisoffers continuous or pulsatile delivery as well as preprogrammedadministration schedules. Factors affecting iontophoretic transportinclude pH, current density, ionic strength, concentration of themolecule to be transported, molecular size of the molecule to betransported, and the method of current application (continuous or pulsecurrent). The charge on the molecule can be controlled by changing thepH of the solution, and so delivery can be adjusted for either cathodalor anodal iontophoresis. Iontophoresis can thus facilitate transport ofthe molecule and may enhance tissue penetration.

In one embodiment, a mammal has a condition associated with aberrantexpression, for instance, aberrant temporal expression or aberrantlevels of expression, of a gene product, e.g., under expression or lackof expression of wild-type (functional) gene product. To prevent,inhibit or treat the condition in the mammal, an implantable device inthe mammal releases via iontophoresis nucleic acid from a polymer matrixwhich includes at least one gene or a portion thereof in senseorientation, e.g., an open reading frame for the gene product or aportion thereof which encodes a gene product with substantially the sameactivity as the full-length gene product. In one embodiment, myocardialtissues of a mammal are contacted with genes which directly orindirectly modulate conduction in the myocardium, e.g., genes for geneproducts which modulate gap junction proteins and/or ion channelproteins, or for transcriptional regulatory proteins which alter gapjunction protein or ion channel protein levels. In another embodiment,atria of mammal having an aberrant If are contacted with an implantabledevice which includes HCN nucleic acid operably linked to a promoter (anexpression cassette) embedded in a polymer matrix. Upon detection of theaberrant I_(f), the HCN gene is delivered to atrial cells in an amountwhich alters the I_(f). Thus, for myocardial conditions, the isolatednucleic acid and/or protein embedded or applied to a polymer matrix isintroduced to the epicardium, endocardium, or pericardium, therebyproviding for localized transmyocardial delivery at a lower dosagerelative to systemic delivery. In another embodiment, the nucleic acidin the polymer matrix encodes a dominant negative gene product which isuseful to decrease expression or levels of an endogenous molecule, forinstance, one which is formed of multiple subunits, one of whichsubunits corresponds to the gene product encoded by the nucleic acid inthe polymer matrix.

In another embodiment, an implantable device in a mammal having acondition associated with under expression of a wild-type (functional)protein releases via iontophoresis the protein from a polymer matrix inan amount which is effective to prevent, inhibit or treat the condition.

Antisense oligonucleotides or polynucleotides can inhibit geneexpression, mainly by binding to messenger RNA of the target gene, andthus have the ability to block the expression of gene productsassociated with a particular condition. Thus, in one embodiment, thenucleic acid in the polymer matrix includes a gene or a portion thereof,e.g., an oligonucleotide, in antisense orientation. In one embodiment,the presence of the nucleic acid in a cell of a mammal with acorresponding endogenous gene inhibits the expression of the endogenousgene. In one embodiment, the endogenous gene encodes a wild-type(functional) gene product which is overexpressed. In another embodiment,the endogenous gene encodes a mutant gene product, e.g., one withaltered activity or a dominant negative.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsdescribe similar components throughout the several views. The drawingsillustrate generally, by way of example, but not by way of limitation,various embodiments discussed in the present document. The drawing arefor illustrative purposes only and not to scale nor anatomicallyaccurate.

FIG. 1 is an illustration of an embodiment of a gene/protein deliverysystem and portions of an environment in which it is used.

FIG. 2 is a block diagram showing one embodiment of the circuit ofportions of the gene/protein delivery system such as shown in FIG. 1.

FIG. 3 is a block diagram showing a further embodiment of the circuit ofportions of the gene/protein delivery system such as shown in FIG. 1.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that the embodiments may be combined, or that otherembodiments may be utilized and that structural, logical and electricalchanges may be made without departing from the spirit and scope of thepresent invention. The following detailed description provides examples,and the scope of the present invention is defined by the appended claimsand their equivalents.

It should be noted that references to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.

Definitions

By “nucleic acid”, “oligonucleotide”, and “polynucleotide” orgrammatical equivalents herein means at least two nucleotides covalentlylinked together.

A “polynucleotide” refers to a polymeric form of nucleotides of anylength, either ribonucleotides or deoxyribonucleotides, or analogsthereof. This term refers to the primary structure of the molecule, andthus includes double- and single-stranded DNA, as well as double- andsingle-stranded RNA, and portions of both double stranded or singlestranded sequence. The polynucleotide may be DNA, both genomic and cDNA,RNA or a hybrid, where the polynucleotide contains any combination ofdeoxyribo-and ribo-nucleotides, and any combination of bases, includinguracil, adenine, thymine, cytosine, guanine, inosine, xathanine andhypoxathanine, etc. Thus, for example, chimeric DNA-RNA molecules may beused such as described in Cole-Strauss et al., Science, 273:1386 (1996)and Yoon et al., Proc. Natl. Acad. Sci. USA, 93:2071 (1996). It alsoincludes modified polynucleotides such as methylated and/or cappedpolynucleotides.

An “oligonucleotide” includes at least 7 nucleotides, preferably 15, andmore preferably 20 or more sequential nucleotides, up to 100nucleotides, either RNA or DNA, which correspond to the complement ofthe non-coding strand, or of the coding strand, of a selected mRNA, orwhich hybridize to the mRNA or DNA encoding the mRNA and remain stablybound under moderately stringent or highly stringent conditions, asdefined by methods well known to the art, e.g., in Sambrook et al., ALaboratory Manual, Cold Spring Harbor Press (1989).

The term “isolated” when used in relation to a nucleic acid, peptide orpolypeptide refers to a nucleic acid sequence, peptide or polypeptidethat is identified and separated from at least one contaminant nucleicacid, polypeptide or other biological component with which it isordinarily associated in its natural source. Isolated nucleic acid,peptide or polypeptide is present in a form or setting that is differentfrom that in which it is found in nature. For example, a given DNAsequence (e.g., a gene) is found on the host cell chromosome inproximity to neighboring genes; RNA sequences, such as a specific mRNAsequence encoding a specific protein, are found in the cell as a mixturewith numerous other mRNAs that encode a multitude of proteins. Theisolated nucleic acid molecule may be present in single-stranded ordouble-stranded form. When an isolated nucleic acid molecule is to beutilized to express a protein, the molecule will contain at a minimumthe sense or coding strand (i.e., the molecule may single-stranded), butmay contain both the sense and anti-sense strands (i.e., the moleculemay be double-stranded).

“Recombinant,” as applied to a polynucleotide, means that thepolynucleotide is the product of various combinations of cloning,restriction and/or ligation steps, and other procedures that result in aconstruct that is distinct from a polynucleotide found in nature.Recombinant as applied to a protein means that the protein is theproduct of expression of a recombinant polynucleotide.

A “gene” generally refers to a polynucleotide or portion of apolynucleotide which includes a sequence for a gene product. For mostsituations, it is desirable for the gene to also comprise a promoteroperably linked to the coding sequence in order to effectively promotetranscription. Enhancers, repressors and other regulatory sequences mayalso be included in order to modulate activity of the gene, as is wellknown in the art.

The terms “polypeptide,” “peptide,” and “protein” are usedinterchangeably to refer to polymers of amino acids of any length. Theseterms also include proteins that are post-translationally modifiedthrough reactions that include glycosylation, acetylation andphosphorylation.

By “DNA” is meant a polymeric form of deoxyribonucleotides (adenine,guanine, thymine, or cytosine) in double-stranded or single-strandedform found, inter alia, in linear DNA molecules (e.g., restrictionfragments), viruses, plasmids, and chromosomes. In discussing thestructure of particular DNA molecules, sequences may be described hereinaccording to the normal convention of giving only the sequence in the 5′to 3′ direction along the nontranscribed strand of DNA (i.e., the strandhaving the sequence complementary to the mRNA). The term capturesmolecules that include the four bases adenine, guanine, thymine, orcytosine, as well as molecules that include base analogues which areknown in the art.

As used herein, the terms “complementary” or “complementarity” are usedin reference to polynucleotides (i.e., a sequence of nucleotides)related by the base-pairing rules. For example, the sequence “A-G-T,” iscomplementary to the sequence “T-C-A.” Complementarity may be “partial,”in which only some of the nucleic acids' bases are matched according tothe base pairing rules. Or, there may be “complete” or “total”complementarity between the nucleic acids. The degree of complementaritybetween nucleic acid strands has significant effects on the efficiencyand strength of hybridization between nucleic acid strands. This is ofparticular importance in amplification reactions, as well as detectionmethods that depend upon binding between nucleic acids.

DNA molecules are said to have “5′ ends” and “3′ ends” becausemononucleotides are reacted to make oligonucleotides or polynucleotidesin a manner such that the 5′ phosphate of one mononucleotide pentosering is attached to the 3′ oxygen of its neighbor in one direction via aphosphodiester linkage. Therefore, an end of an oligonucleotide orpolynucleotide is referred to as the “5′ end” if its 5′ phosphate is notlinked to the 3′ oxygen of a mononucleotide pentose ring and as the “3′end” if its 3′ oxygen is not linked to a 5′ phosphate of a subsequentmononucleotide pentose ring. As used herein, a nucleic acid sequence,even if internal to a larger oligonucleotide or polynucleotide, also maybe said to have 5′ and 3′ ends. In either a linear or circular DNAmolecule, discrete elements are referred to as being “upstream” or 5′ ofthe “downstream” or 3′ elements. This terminology reflects the fact thattranscription proceeds in a 5′ to 3′ fashion along the DNA strand. Thepromoter and enhancer elements that direct transcription of a linkedgene are generally located 5′ or upstream of the coding region. However,enhancer elements can exert their effect even when located 3′ of thepromoter element and the coding region. Transcription termination andpolyadenylation signals are located 3′ or downstream of the codingregion.

“Homology” refers to the percent of identity between two polynucleotidesor two polypeptides. The correspondence between one sequence and toanother can be determined by techniques known in the art. For example,homology can be determined by a direct comparison of the sequenceinformation between two polypeptide or polynucleotide molecules byaligning the sequence information and using readily available computerprograms. Alternatively, homology can be determined by hybridization ofpolynucleotides under conditions which form stable duplexes betweenhomologous regions, followed by digestion with single strand-specificnuclease(s), and size determination of the digested fragments. Two DNA,or two polypeptide, sequences are “substantially homologous” to eachother when at least about 80%, preferably at least about 90%, and mostpreferably at least about 95% of the nucleotides, or amino acids,respectively match over a defined length of the molecules, as determinedusing the methods above.

By “expression construct” or “expression cassette” is meant a nucleicacid molecule that is capable of directing transcription. An expressionconstruct includes, at the least, a promoter. Additional elements, suchas an enhancer, and/or a transcription termination signal, may also beincluded.

The term “heterologous” as it relates to nucleic acid sequences such asgene sequences and control sequences, denotes sequences that are notnormally joined together, and/or are not normally associated with aparticular cell. Thus, a “heterologous” region of a nucleic acidconstruct or a vector is a segment of nucleic acid within or attached toanother nucleic acid molecule that is not found in association with theother molecule in nature. For example, a heterologous region of anucleic acid construct could include a coding sequence flanked bysequences not found in association with the coding sequence in nature,i.e., a heterologous promoter. Another example of a heterologous codingsequence is a construct where the coding sequence itself is not found innature (e.g., synthetic sequences having codons different from thenative gene). Similarly, a cell transformed with a construct which isnot normally present in the cell would be considered heterologous forpurposes of this invention.

The term “control elements” refers collectively to promoter regions,polyadenylation signals, transcription termination sequences, upstreamregulatory domains, origins of replication, internal ribosome entrysites (“IRES”), enhancers, splice junctions, and the like, whichcollectively provide for the replication, transcription,post-transcriptional processing and translation of a coding sequence ina recipient cell. Not all of these control elements need always bepresent so long as the selected coding sequence is capable of beingreplicated, transcribed and translated in an appropriate host cell.

The term “promoter region” is used herein in its ordinary sense to referto a nucleotide region comprising a DNA regulatory sequence, wherein theregulatory sequence is derived from a gene which is capable of bindingRNA polymerase and initiating transcription of a downstream (3′direction) coding sequence. Thus, a “promoter,” refers to apolynucleotide sequence that controls transcription of a gene or codingsequence to which it is operably linked. A large number of promoters,including constitutive, inducible and repressible promoters, from avariety of different sources, are well known in the art.

By “enhancer element” is meant a nucleic acid sequence that, whenpositioned proximate to a promoter, confers increased transcriptionactivity relative to the transcription activity resulting from thepromoter in the absence of the enhancer domain. Hence, an “enhancer”includes a polynucleotide sequence that enhances transcription of a geneor coding sequence to which it is operably linked. A large number ofenhancers, from a variety of different sources are well known in theart. A number of polynucleotides which have promoter sequences (such asthe commonly-used CMV promoter) also have enhancer sequences.

By “cardiac-specific enhancer or promoter” is meant an element, which,when operably linked to a promoter or alone, respectively, directs geneexpression in a cardiac cell and does not direct gene expression in alltissues or all cell types. Cardiac-specific enhancers or promoters maybe naturally occurring or non-naturally occurring. One skilled in theart will recognize that the synthesis of non-naturally occurringenhancers or promoters can be performed using standard oligonucleotidesynthesis techniques.

“Operably linked” refers to a juxtaposition, wherein the components sodescribed are in a relationship permitting them to function in theirintended manner. By “operably linked” with reference to nucleic acidmolecules is meant that two or more nucleic acid molecules (e.g., anucleic acid molecule to be transcribed, a promoter, and an enhancerelement) are connected in such a way as to permit transcription of thenucleic acid molecule. A promoter is operably linked to a codingsequence if the promoter controls transcription of the coding sequence.Although an operably linked promoter is generally located upstream ofthe coding sequence, it is not necessarily contiguous with it. Anenhancer is operably linked to a coding sequence if the enhancerincreases transcription of the coding sequence. Operably linkedenhancers can be located upstream, within or downstream of codingsequences. A polyadenylation sequence is operably linked to a codingsequence if it is located at the downstream end of the coding sequencesuch that transcription proceeds through the coding sequence into thepolyadenylation sequence. “Operably linked” with reference to peptideand/or polypeptide molecules is meant that two or more peptide and/orpolypeptide molecules are connected in such a way as to yield a singlepolypeptide chain, i.e., a fusion polypeptide, having at least oneproperty of each peptide and/or polypeptide component of the fusion.Thus, a signal or targeting peptide sequence is operably linked toanother protein if the resulting fusion is secreted from a cell as aresult of the presence of a secretory signal peptide or into anorganelle as a result of the presence of an organelle targeting peptide.

“Gene delivery,” “gene transfer,” and the like as used herein, are termsreferring to the introduction of an exogenous polynucleotide (sometimesreferred to as a “transgene”) into a host cell, irrespective of themethod used for the introduction. Such methods include a variety ofwell-known techniques such as vector-mediated gene transfer (by, e.g.,viral infection/transfection, or various other protein-based orlipid-based gene delivery complexes) as well as techniques facilitatingthe delivery of “naked” polynucleotides (such as electroporation,iontophoresis, “gene gun” delivery and various other techniques used forthe introduction of polynucleotides). The introduced polynucleotide maybe stably or transiently maintained in the host cell. In one embodiment,e.g., with isolated nucleic acid which is not extrachromosomallymaintained or integrated into the genome of a cell, the introducedpolynucleotide is transiently maintained in the cell. Stable maintenancetypically requires that the introduced polynucleotide either contains anorigin of replication compatible with the host cell or integrates into areplicon of the host cell such as an extrachromosomal replicon (e.g., aplasmid) or a nuclear or mitochondrial chromosome.

By “transgene” is meant any piece of a nucleic acid molecule (forexample, DNA) which is inserted by artifice into a cell eithertransiently or permanently, and becomes part of the organism ifintegrated into the genome or maintained extrachromosomally. Such atransgene may include a gene which is partly or entirely heterologous(i.e., foreign) to the transgenic organism, or may represent a genehomologous to an endogenous gene of the organism.

“In vivo” gene/protein delivery, gene/protein transfer, gene/proteintherapy and the like as used herein, are terms referring to theintroduction of an exogenous (isolated) polynucleotide or proteindirectly into the body of an organism, such as a human or non-humanmammal, whereby the exogenous polynucleotide or protein is introduced toa cell of such organism in vivo.

A “vector” (sometimes referred to as gene delivery or gene transfer“vehicle”) refers to a macromolecule or complex of molecules comprisinga polynucleotide or protein to be delivered to a host cell, either invitro or in vivo. Vectors include, for example, expression vectors,viral vectors (such as adenoviruses (“Ad”), adeno-associated viruses(AAV), lentiviruses, poxviruses, papilloma viruses, herpesviruses, andretroviruses), liposomes and other lipid-containing complexes, and othermacromolecular complexes capable of mediating or enhancing delivery of apolynucleotide or protein to a host cell. Vectors can also compriseother components or functionalities that further modulate gene deliveryand/or gene expression, or that otherwise provide beneficial propertiesto the targeted cells. Such other components include, for example,components that influence binding or targeting to cells (includingcomponents that mediate cell-type or tissue-specific binding);components that influence uptake of nucleic acid or protein by the cell;components that influence localization of the polynucleotide or proteinwithin the cell after uptake (such as agents mediating nuclearlocalization); and components that influence expression ofpolynucleotides. Such components also might include markers, such asdetectable and/or selectable markers that can be used to detect orselect for cells that have taken up and are expressing the introducednucleic acid. Such components can be provided as a natural feature ofthe vector (such as the use of certain viral vectors which havecomponents or functionalities mediating binding and uptake), or vectors.can be modified to provide such functionalities. A large variety of suchvectors are known in the art and are generally available.

A “therapeutic polynucleotide”, “therapeutic gene” or “therapeuticprotein” refers to a nucleotide sequence or amino acid sequence that iscapable, when transferred to cells of an individual, of eliciting aprophylactic, curative or other beneficial effect in the individual.

The term “corresponds to” is used herein to mean that a polynucleotideor protein sequence is homologous (i.e., may be similar or identical,not strictly evolutionarily related) to all or a portion of a referencepolynucleotide or protein sequence. In contradistinction, the term“complementary to” is used herein to mean that the complementarypolynucleotide sequence is able to hybridize to the other strand. Asoutlined below, preferably, the homology between the two sequences is atleast 70%, preferably 85%, and more preferably 95%, identical.

The terms “substantially corresponds to” or “substantial identity” or“homologous” as used herein denotes a characteristic of a nucleic acidor protein sequence, wherein a nucleic acid or protein sequence has atleast about 70% sequence identity as compared to a reference sequence,typically at least about 85% sequence identity, and preferably at leastabout 95% sequence identity, as compared to a reference sequence. Thereference sequence may be a subset of a larger sequence, such as aportion of a gene or flanking sequence, or portion of protein. However,the reference sequence is at least 20 nucleotides long, typically atleast about 30 nucleotides long, and preferably at least about 50 to 100nucleotides long, or, for peptides or polypeptides, at least 7 aminoacids long, typically at least 10 amino acids long, and preferably atleast 20 to 30 amino acids long. “Substantially complementary” as usedherein refers to a nucleotide sequence that is complementary to asequence that substantially corresponds to a reference sequence.

“Specific hybridization” is defined herein as the formation of hybridsbetween a polynucleotide which may include substitutions, deletion,and/or additions as compared to a reference sequence and a selectedtarget nucleic acid sequence, wherein the polynucleotide preferentiallyhybridizes to a target nucleic acid sequence such that, for example, atleast one discrete band can be identified on a Northern or Southern blotof DNA prepared from cells that contain the target nucleic acidsequence. It is evident that optimal hybridization conditions will varydepending upon the sequence composition and length(s) of thepolynucleotide(s) and target(s), and the experimental method selected bythe practitioner. Various guidelines may be used to select appropriatehybridization conditions (see, Maniatis et al., 1989 and Berger andKimmel, 1987).

The term “wild-type” refers to a gene or gene product that has thecharacteristics of that gene or gene product when isolated from anaturally occurring source. A wild-type gene is that which is mostfrequently observed in a population and is thus arbitrarily designatedthe “normal” or “wild-type” form of the gene. In contrast, the term“modified” or “mutant” refers to a gene or gene product that displaysmodifications in sequence and or functional properties (i.e., alteredcharacteristics) when compared to the wild-type gene or gene product. Itis noted that naturally-occurring mutants can be isolated; these areidentified by the fact that they have altered characteristics whencompared to the wild-type gene or gene product.

As used herein, the term “disease allele” refers to an allele of a genethat is capable of producing a recognizable disease. A disease allelemay be dominant or recessive and may produce disease directly or whenpresent in combination with a specific genetic background orpre-existing pathological condition. A disease allele may be present inthe gene pool (an inherited disease allele) or may be generated de novoin an individual by somatic mutation (an acquired disease allele).

“Vasculature” or “vascular” are terms referring to the system of vesselscarrying blood (as well as lymph fluids) throughout the mammalian body.

“Blood vessel” refers to any of the vessels of the mammalian vascularsystem, including arteries, arterioles, capillaries, venules, veins,sinuses, and vasa vasorum.

“Artery” refers to a blood vessel through which blood passes away fromthe heart. Coronary arteries supply the tissues of the heart itself,while other arteries supply the remaining organs of the body. Thegeneral structure of an artery consists of a lumen surrounded by amulti-layered arterial wall.

By “mammal” is meant any member of the class Mammalia including, withoutlimitation, humans and nonhuman primates such as chimpanzees and otherapes and monkey species; farm animals such as cattle, sheep, pigs, goatsand horses; domestic mammals such as dogs and cats; laboratory animalsincluding rodents such as mice, rats, rabbits and guinea pigs, and thelike.

By “derived from” is meant that a nucleic acid molecule was either madeor designed from a parent nucleic acid molecule, the derivativeretaining substantially the same functional features of the parentnucleic acid molecule, e.g., encoding a gene product with substantiallythe same activity as the gene product encoded by the parent nucleic acidmolecule from which it was made or designed.

The term “exogenous,” when used in relation to a protein, gene, nucleicacid, or polynucleotide in a cell or organism refers to a protein, gene,nucleic acid, or polynucleotide which has been introduced into the cellor organism by artificial or natural means, or in relation a cell refersto a cell which was isolated and subsequently introduced to other cellsor to an organism by artificial or natural means. An exogenous nucleicacid may be from a different organism or cell, or it may be one or moreadditional copies of a nucleic acid which occurs naturally within theorganism or cell. An exogenous cell may be from a different organism, orit may be from the same organism. By way of a non-limiting example, anexogenous nucleic acid is in a chromosomal location different from thatof natural cells, or is otherwise flanked by a different nucleic acidsequence than that found in nature.

By “growth factor” is meant an agent that, at least, promotes cellgrowth or induces phenotypic changes.

The term “angiogenic” means an agent that alone or in combination withother agents induces angiogenesis, and includes, but is not limited to,fibroblast growth factor (FGF), vascular endothelial growth factor(VEGF), hepatocyte growth factor, angiogenin, transforming growth factor(TGF), tissue necrosis factor (TNF, e.g., TNF-α), platelet derivedgrowth factor (PDGF), granulocyte colony stimulatory factor (GCSF),placental GF, IL-8, proliferin, angiopoietin, e.g., angiopoietin-1 andangiopoietin-2, thrombospondin, ephrin-A1, E-selectin, leptin andheparin affinity regulatory peptide.

“Cardiovascular conditions” include, but are not limited to, coronaryartery disease/ischemia, coronary artery disease (CAD), ischemia, angina(chest pain), thrombosis, coronary thrombosis, myocardial infarction(MI), silent ischemia, stenosis/restenosis, transient ischemic attack(TIA), atherosclerosis, peripheral vascular disease, bradyarrhythmia,e.g., bradyarrhythmia, bradycardia, sick sinus rhythm (Sick SinusSyndrome), sinus bradycardia, sinoatrial block, asystole, sinus arrest,syncope, first degree atrio-ventricular (AV) block, second degreeatrio-ventricular (AV) block, third degree atrio-ventricular (AV) block,chronotropic incompetence, tachyarrhythmia, e.g., tachyarrhythmia,tachycardia, fibrillation, flutter, atrial fibrillation, atrial flutter,familial atrial fibrillation, paroxysmal atrial fibrillation, permanentatrial fibrillation, persistent atrial fibrillation, supraventriculartachyarrhythmias, sinus tachycardia, reentry (reentrant arrhythmias), AVnodal reentry, focal arrhythmia, ectopy, ventricular fibrillation (VF),ventricular tachycardia (VT), Wolff-Parkinson-White Syndrome (WPW) andsudden cardiac death, heart failure, e.g., heart failure,cardiomyopathy, congestive heart failure, hypertrophic cardiomyopathy,remodeling, non-ischemic cardiomyopathy, dilated cardiomyopathy,restrictive cardiomyopathy, diastolic heart failure, systolic heartfailure, and chronic heart failure, heart block/electrical disorders,e.g., atrioventricular (AV) block, bundle branch block (BBB), leftbundle branch block (LBBB), right bundle branch block (RBBB), Long QTSyndrome (LQTS), premature ventricular contraction (PVC), electricalremodeling, intraventricular conduction defect, and hemiblock,hemodynamic deficiency, e.g., hypertension, hypotension, leftventricular dysfunction, low ejection fraction, low cardiac output, andlow stroke volume, sudden cardiac death, cardiac arrest, sudden cardiacdeath (SCD), ventricular fibrillation, and pump failure, as well asbacterial endocarditis, viral myocarditis, pericarditis, rheumatic heartdisease, and syncope. In particular, a cardiovascular conditionincludes, but is not limited to, arrhythmia, e.g., atrial fibrillation,ventricular fibrillation or bradycardia, ischemia, heart failure andhyperplasia not associated with neoplastic disease, which condition maybe associated with ventricular remodeling, diastolic dysfunction,aberrant body temperature, aberrant or altered pressure, e.g., alteredvenous, left ventricular or left atrial pressure, aberrant or alteredheart rate or sounds, aberrant or altered electrogram, aberrant oraltered cardiac metabolism, such as altered blood pH, glucose, pO₂,pCO₂, minute ventilation, creatine, CRP, Mef2A, creatine kinase orcreatine kinase MB levels, aberrant or altered pulmonary or thoracicimpedence, aberrant or altered stroke volume, aberrant or alteredneurohormone levels, aberrant or altered electrical activity, aberrantor altered sympathetic nerve activity, aberrant or altered renal output,aberrant or altered filtration rate, aberrant or altered angiotensin IIlevels, or aberrant or altered respiratory sounds, and the like.

“Treatment” or “therapy” as used herein refers to administering, to anindividual patient, agents that are capable of eliciting a prophylactic,curative or other beneficial effect in the individual.

“Gene therapy” as used herein refers to administering, to an individualpatient, vectors comprising a therapeutic gene.

A “user” includes a physician or other caregiver using the gene/proteindelivery system to treat a patient.

General Overview

The present invention provides a system to transiently deliver one ormore gene- and/or one or more protein-based therapeutic agents, as wellas nongene-, nonprotein-based therapeutic agents, in a spatiallycontrolled manner to cells or tissue of a mammal. The isolated nucleicacid, when introduced and optionally expressed in a cell, or theisolated protein when introduced to a cell, yields a cell with adifferent phenotype than a corresponding cell which is not contactedwith the isolated nucleic acid or isolated protein. In some embodiments,the isolated nucleic acid or protein will be other than a naturallyoccurring sequence. In one embodiment, the mammal to be treated has oris at risk of having a cardiovascular condition. For example, the mammalmay have or be at risk of having atrial fibrillation, ventriculartachycardia, heart failure, ischemia, bradycardia or hyperplasia.

This document also discusses a gene/protein delivery system thatincludes an implantable iontophoresis gene/protein delivery device andan implantable pulse generator. In this document, “gene/proteindelivery” includes delivery of genes, proteins, and optionally othermoieties useful to inhibit, prevent or treat at least one symptom(manifestation) of a condition, e.g., a cardiovascular condition. Theimplantable iontophoresis gene/protein delivery device is capable ofdelivering one or more genes and/or one or more proteins and optionallyone or more non-nucleic acid, non-protein based agents to a mammal. Asused herein, a “gene” includes a polynucleotide which may include afull-length open reading frame which encodes a gene product (senseorientation) or a portion thereof (sense orientation) which encodes agene product with substantially the same activity as the gene productencoded by the full-length open reading frame, the complement of thepolynucleotide, e.g., the complement of the full-length open readingframe (antisense orientation) and optionally linked 5′ and/or 3′noncoding sequence(s) or a portion thereof, e.g., an oligonucleotide,which is useful to inhibit transcription, stability or translation of acorresponding mRNA. In one embodiment, a polynucleotide of the inventionincludes operably linked transcriptional elements including, but notlimited to, a promoter, an enhancer, an intron, a Kozak sequence, or atranscription termination sequence. In another embodiment, apolynucleotide of the invention does not include a transcriptionalelement. In one embodiment, a polynucleotide of the invention includesmodified nucleotides, e.g., those with one or more modified sugars,bases or phosphate groups. Thus, a nucleic acid of the present inventionmay contain phosphodiester bonds, although in some cases nucleic acidanalogs are included that may have alternate backbones, comprising, forexample, phosphoramide (Beaucage et al., Methods Mol. Biol., 20:33(1993); Letsinger, J. Org. Chem., 35:3800 (1970); Sprinzl et al., Eur.J. Biochem., 81:579 (1977); Letsinger et al., Nucl. Acids Res., 14:3487(1986)), phosphorothioate, phosphorodithioate, O-methylphosphoroamiditelinkages, including morpholino modified oligo- or poly-nucleotides (Kanget al., Biopolymers, 32:1351 (1992); Summerton et al., Antisense Nucl.Acid. Drug Dev., 7:187 (1997); U.S. Pat. Nos. 5,142,047 and 5,185,444),and peptide nucleic acid backbones and linkages (Nielsen, Orig. LifeEvol. Biosph., 23:323 (1993)). Modifications of the ribose-phosphatebackbone or bases may be done to facilitate the addition of othermoieties such as chemical constituents, including 2′ O-methyl and 5′modified substituents, and/or to increase the stability and half-life ofsuch molecules in physiological environments. In particular, forantisense nucleic acid which is not expressed from a vector, basemodifications (Herdewijn et al., Antisense Nucl. Acid. Drug Dev., 10:297(2000); Mangos et al., Curr. Topics Med. Chem., 7, 1147 (2002)); sugarmodifications (Urban et al., Farmaco, 58:243 (2003)), e.g., arabinosederivatives (Wilds et al., Bioconj. Chem., 10:299 (1999)); and phosphatemodifications such as 2′-methoxyethoxy (Kimber et al., Reprod. Biomed.Online, 6:318 (2003)); and/or the use of5-(N-aminohexyl)carbamoyl-2′-O-methyluridine (Ito et al., NAR, 31:2514(2003)), may be employed to enhance stability in vivo. Moreover, thenucleic acid may be a chimera, e.g., made up of DNA and RNA, e.g.,deoxyribonucleotides and ribonucleotides, e.g.,2′-O-methyl-ribonucleotides (see published U.S. patent application20030045830.

The isolated nucleic acid or protein may be prepared via recombinantmeans or chemical synthesis. For example, the isolated nucleic acid maybe a plasmid, viral vector, cosmid, phage, BAC, YAC or other artificialchromosome, isolated nucleic acid from a cell transfected with a plasmidor other vector or infected with a recombinant virus, or in vitrotranscribed nucleic acid. As described above, in one embodiment, theisolated nucleic acid includes modified nucleotides, e.g., those whichare more stable to hydrolysis, which nucleic acid is prepared viachemical synthesis. In one embodiment, the isolated nucleic acid iscapable of being transcribed by RNA polymerase and hybridizing to targetnucleic acid while in other embodiments, the isolated nucleic acid iscapable of hybridizing to target nucleic acid, e.g., antisense nucleicacid, but not of being transcribed in vivo.

A protein useful in the system and methods of the invention can besynthesized in vitro, e.g., by the solid phase peptide synthetic methodor by recombinant DNA approaches. The solid phase peptide syntheticmethod is an established and widely used method, which is described inthe following references: Stewart et al., Solid Phase Peptide Synthesis,W. H. Freeman Co., San Francisco (1969); Merrifield, J. Am. Chem. Soc.,85 2149 (1963); Meienhofer in “Hormonal Proteins and Peptides,” ed.; C.H. Li, Vol. 2 (Academic Press, 1973), pp. 48-267; Bavaay and Merrifield,“The Peptides,” eds. E. Gross and F. Meienhofer, Vol. 2 (Academic Press,1980) pp. 3-285; and Clark-Lewis et al., Meth. Enzymol., 287, 233(1997). These proteins can be further purified by fractionation onimmunoaffinity or ion-exchange columns; ethanol precipitation; reversephase HPLC; chromatography on silica or on an anion-exchange resin suchas DEAE; chromatofocusing; SDS-PAGE; ammonium sulfate precipitation; gelfiltration using, for example, Sephadex G-75; or ligand affinitychromatography.

Once isolated and characterized, derivatives, e.g., chemically derivedderivatives, of a given protein can be readily prepared. For example,amides of proteins may also be prepared by techniques well known in theart for converting a carboxylic acid group or precursor, to an amide. Apreferred method for amide formation at the C-terminal carboxyl group isto cleave the protein from a solid support with an appropriate amine, orto cleave in the presence of an alcohol, yielding an ester, followed byaminolysis with the desired amine.

Salts of carboxyl groups of a protein may be prepared in the usualmanner by contacting the protein with one or more equivalents of adesired base such as, for example, a metallic hydroxide base, e.g.,sodium hydroxide; a metal carbonate or bicarbonate base such as, forexample, sodium carbonate or sodium bicarbonate; or an amine base suchas, for example, triethylamine, triethanolamine, and the like.

N-acyl derivatives of an amino group of a protein may be prepared byutilizing an N-acyl protected amino acid for the final condensation, orby acylating a protected or unprotected protein. O-acyl derivatives maybe prepared, for example, by acylation of a free hydroxy protein orprotein resin. Either acylation may be carried out using standardacylating reagents such as acyl halides, anhydrides, acyl imidazoles,and the like. Both N— and O-acylation may be carried out together, ifdesired.

Formyl-methionine, pyroglutamine and trimethyl-alanine may besubstituted at the N-terminal residue of the protein. Otheramino-terminal modifications include aminooxypentane modifications (seeSimmons et al., Science, 276, 276 (1997)).

In addition, the amino acid sequence of a protein can be modified so asto result in a variant. The modification includes the substitution of atleast one amino acid residue in the protein for another amino acidresidue, including substitutions which utilize the D rather than L form,as well as other well known amino acid analogs, e.g., unnatural aminoacids such as α,α-disubstituted amino acids, N-alkyl amino acids, lacticacid, and the like. These analogs include phosphoserine,phosphothreonine, phosphotyrosine, hydroxyproline,gamma-carboxyglutamate; hippuric acid, octahydroindole-2-carboxylicacid, statine, 1,2,3,4,-tetrahydroisoquinoline-3-carboxylic acid,penicillamine, omithine, citruline, α-methyl-alanine,para-benzoyl-phenylalanine, phenylglycine, propargylglycine, sarcosine,ε-N,N,N-trimethyllysine, ε-N-acetyllysine, N-acetylserine,N-formylmethionine, 3-methylhistidine, 5-hydroxylysine,ω-N-methylarginine, and other similar amino acids and imino acids andtert-butylglycine.

One or more of the residues of the protein can be altered, so long asthe resulting variant has substantially the same activity as that of theunmodified (functionally active) protein. For example, it is preferredthat the variant has at least about 80% or more, at least 90%, thebiological activity of the corresponding unmodified protein.Conservative amino acid substitutions are preferred. For example,aspartic-glutamic as acidic amino acids; lysine/arginine/histidine asbasic amino acids; leucine/isoleucine/methionine/alanine/valine/glycineas hydrophobic amino acids; serine/threonine as hydrophilic amino acids.Conservative amino acid substitution also includes groupings based onside chains. In another example, a group of amino acids having aliphaticside chains is glycine, alanine, valine, leucine, and isoleucine; agroup of amino acids having aliphatic-hydroxyl side chains is serine andthreonine; a group of amino acids having amide-containing side chains isasparagine and glutamine; a group of amino acids having aromatic sidechains is phenylalanine, tyrosine, and tryptophan; a group of aminoacids having basic side chains is lysine, arginine, and histidine; and agroup of amino acids having sulfur-containing side chains is cysteineand methionine. For example, it is reasonable to expect that replacementof a leucine with an isoleucine or valine, an aspartate with aglutamate, a threonine with a serine, or a similar replacement of anamino acid with a structurally related amino acid will not have a majoreffect on the properties of the resulting variant. Whether an amino acidchange results in a functional protein can readily be determined byassaying the specific activity of the variant.

Amino acid substitutions falling within the scope of the invention, are,in general, accomplished by selecting substitutions that do not differsignificantly in their effect on maintaining (a) the structure of thepeptide backbone in the area of the substitution, (b) the charge orhydrophobicity of the molecule at the target site, or (c) the bulk ofthe side chain. Naturally occurring residues are divided into groupsbased on common side-chain properties:

(1) hydrophobic: norleucine, met, ala, val, leu, ile;

(2) neutral hydrophilic: cys, ser, thr;

(3) acidic: asp, glu;

(4) basic: asn, gln, his, lys, arg;

(5) residues that influence chain orientation: gly, pro; and

(6) aromatic; trp, tyr, phe.

The invention also envisions variants with non-conservativesubstitutions. Non-conservative substitutions entail exchanging a memberof one of the classes described above for another.

Acid addition salts of a protein or of amino residues of the protein maybe prepared by contacting the protein or amine with one or moreequivalents of the desired inorganic or organic acid, such as, forexample, hydrochloric acid. Esters of carboxyl groups of the proteinsmay also be prepared by any of the usual methods known in the art.

Moreover, it is also envisioned that the proteins are modified in amanner that increases their stability in vivo, e.g., their half-life orbioavailability. Methods to prepare such derivatives are well known tothe art. One method to stabilize peptides is to prepare derivativeswhich are cyclized peptides (see EPA 471,453 (amide bonds), such as thatbetween lysine and aspartic acid side chains; EPA 467,701 (disulfidebonds); EPA 467,699 (thioether bonds). Other modifications which mayincrease in vivo stability are disclosed in Jameson et al. (Nature, 368,744 (1994)); U.S. Pat. No. 4,992,463; U.S. Pat. No. 5,596,078 and U.S.Pat. No. 5,091,396.

The gene/protein delivery system of the invention detects a certainphysiological signal, e.g., a change in a particular physiologicalparameter, indicative of a condition or the onset of a condition, e.g.,a condition treatable by gene and/or protein therapy, and, in responseto the detection, delivers an effective amount of the gene(s) and/orprotein(s). Though discussed specifically as part of a cardiac rhythmmanagement system, the gene/protein delivery system may be employed forall in vivo gene/protein therapies.

FIG. 1 is an illustration of an embodiment of a gene/protein deliverysystem 100 and portions of an environment in which it is used. System100 includes implantable system 105, external system 155, and telemetrylink 140 providing for communication between implantable system 105 andexternal system 155.

Implantable system 105 includes, among other things, implantable CRMdevice 110, lead system 108, and implantable iontophoresis gene/proteindelivery device 130. As shown in FIG. 1, implantable CRM device 110 isimplanted in body 102. In one embodiment, implantable CRM device 110includes a gene/protein delivery controller. Gene/protein deliverydevice 130 is attached to heart 101. Lead system 108 includes one ormore leads providing for communication between implantable CRM device110 and ene/protein delivery device 130. In one embodiment, lead system108 provides for wired communication between implantable CRM device 110and gene/protein delivery device 130. In one embodiment, lead system 108provides for communication between implantable CRM device 110 andgene/protein delivery device 130 through tissue conduction of anelectric signal. In various embodiments, implantable CRM device 110 alsoincludes a pacemaker, a cardioverter/defibrillator, a cardiacresynchronization therapy (CRT) device, a cardiac remodeling controltherapy (RCT) device, a drug delivery device or a drug deliverycontroller, a cell therapy device, or any other implantable medicaldevice. Lead system 108 further includes leads for sensing physiologicalsignals and delivering pacing pulses, cardioversion/defibrillationshocks, and/or pharmaceutical or other substances.

External system 155 includes external device 150, network 160, andremote device 170. External device 150 is within the vicinity ofimplantable CRM device 110 and communicates with implantable CRM device110 bi-directionally via telemetry link 140. Remote device 170 is in aremote location and communicates with external device 150bi-directionally via network 160, thus allowing a user to monitor andtreat a patient from a distant location.

System 100 allows gene/protein delivery to be triggered by any one ofimplantable CRM device 110, external device 150, or remote device 170.In one embodiment, implantable CRM device 110 triggers gene/proteindelivery upon detecting a predetermined signal or condition. In anotherembodiment, external device 150 or remote device 170 triggersgene/protein delivery upon detecting a condition from a signaltransmitted from implantable CRM device 110. In one specific embodiment,external system 155 includes a processor running a therapy decisionalgorithm to determine whether and when to trigger gene/proteindelivery. In another specific embodiment, external system 155 includes auser interface to present signals acquired by implantable CRM device 155and/or the detected abnormal condition to a user and receives commandsfrom the user for triggering gene/protein delivery. In another specificembodiment, the user interface includes a user input incorporated intoexternal device 150 to receive commands from the user and/or the patienttreated with system 100. For example, the patient may be instructed toenter a command for a gene/protein delivery when he senses certainsymptoms, and another person near the patient may do the same uponobserving the symptoms.

FIG. 2 is a block diagram showing one embodiment of the circuit ofportions of system 100 including implantable CRM device 110, lead system108, and gene/protein delivery device 130. In one embodiment, leadsystem 108 provides for an electrical connection between implantable CRMdevice 110 and gene/protein delivery device 130, such that theimplantable CRM device transmits a voltage or current signal to thegene/protein delivery device to control gene/protein delivery. Inanother embodiment, lead system 108 allows an electrical field to becreated at or near gene/protein delivery device 130 by an electricalsignal generated from implantable CRM device 110 to control gene/proteindelivery.

Gene/protein delivery device 130 includes polymer matrix 232 andisolated nucleic acid which encodes at least one gene product, isolatednucleic acid which binds at least one selected mRNA, or isolatedprotein, or a combination thereof. The isolated nucleic acid and/orprotein are released from gene/protein delivery device 232 in responseto the gene/protein delivery control signal transmitted from implantableCRM device 110. In one embodiment, gene/protein delivery device 130includes an epicardial patch for delivering the gene(s)/protein(s) intocardiac tissue. In another embodiment, gene/protein delivery device 130is incorporated into a vascular device such as a stent to release thegene(s) and/or protein(s) into the blood. Examples of a drug deliverydevice that employs iontophoresis are described in U.S. Pat. No.5,041,107, “ELECTRICALLY CONTROLLABLE NON-OCCLUDING, BODY IMPLANTABLEDRUG DELIVERY SYSTEM” and U.S. Pat. No. 6,689,117, “DRUG DELIVERY SYSTEMFOR IMPLANTABLE MEDICAL DEVICE”, both assigned to Cardiac Pacemakers,Inc., which are incorporated herein by reference in their entirety.

Implantable CRM device 110 includes sensor 212, event detector 213, andimplant controller 214. Sensor 212 senses a physiological signalindicative of a condition which may be inhibited or treated withgene/protein delivery. Event detector 213 detects the condition. Implantcontroller 214 includes gene/protein delivery control module 215, whichtransmits a signal to gene/protein delivery device 130 to triggergene/protein delivery in response to a detected condition. In oneembodiment, gene/protein delivery device 130 includes polymer matrix 232that contains one or more genes, e.g., two or more different, and/or oneor more proteins, and releases the gene(s) and/or protein(s) in responseto an applied electrical field. In one embodiment, an electrical fieldis applied to polymer matrix 232 as a voltage delivered through leadsystem 108. In another embodiment, such as when gene/protein deliverydevice 130 is not directly wired to an implantable CRM device, anelectrical field is applied to polymer matrix 232 by conduction throughthe tissue of body 102.

In one embodiment, sensor 212 includes a cardiac sensing circuit thatsenses one or more electrograms, and event detector 213 detects anarrhythmia from the one or more electrograms. In one embodiment, eventdetector 213 detects the arrhythmia by detecting heart rate andcomparing the heart rate to one or more threshold rates. A bradycardiacondition is detected when the heart rate falls below a bradycardiathreshold. A tachycardia condition is detected when the heart rateexceeds a tachycardia threshold. In a further embodiment, event detector213 detects the arrhythmia by comparing morphological features of theelectrogram to one or more predetermined templates. Event detector 213includes one or more of a bradycardia detector, tachycardia detector,fibrillation detector, and any other arrhythmia detectors. In onespecific embodiment, event detector 213 includes an atrial fibrillationdetector. In another specific embodiment, event detector 213 includes aventricular fibrillation detector.

In one embodiment, sensor 212 senses a physiological signal indicativeof ischemia, and event detector 213 includes an ischemia detector. Inone specific embodiment, sensor 212 senses an electrogram and eventdetector 213 runs an automatic ischemia detection algorithm to detect anischemic condition from the electrogram. One specific example of anelectrogram-based ischemia detector is discussed in Zhu et al., U.S.patent application Ser. No. 09/962,852, “EVOKED RESPONSE SENSING FORISCHEMIA DETECTION,” filed on Sep. 25, 2001, assigned to CardiacPacemakers, Inc., which is incorporated herein by reference in itsentirety. In another embodiment, sensor 212 includes an electricalimpedance based sensor using a low carrier frequency (e.g., 100 Hz), andevent detector 213 runs an automatic ischemia detection algorithm todetect an ischemic condition from the electrical impedance signal.Tissue electrical impedance has been shown to increase significantlyduring ischemia, as discussed in Min et al. (International Journal ofBioelectromagnetism, 5:53 (2003)). Sensor 212 senses low frequencyelectrical impedance signal between electrodes interposed in the heart.Event detector 213 detects the ischemia as abrupt changes in impedance(such as abrupt increases in value). In another specific embodiment,sensor 212 includes a local heart motion based sensor utilizing anaccelerometer located within a lead body positioned on or in the heart,and event detector 213 runs an automatic ischemia detection algorithm todetect an ischemic condition from the acceleration signal. Eventdetector 213 detects ischemia as an abrupt decrease in the amplitude oflocal cardiac accelerations.

In one embodiment, sensor 212 includes a metabolic sensor that senses ametabolic signal indicative of a cardiac metabolic level (rate ofmetabolism of cardiac cells). Examples of the metabolic sensor includebut are not limited to a pH sensor, an oxygen pressure (PO₂) sensor, acarbon dioxide pressure (PCO₂) sensor, a glucose sensor, a creatinesensor, a C-creative protein sensor, a creatine kinase sensor, acreatine kinase-MB sensor, or any combination of such sensors. Eventdetector 213 determines the cardiac metabolic level from the metabolicsignal and compares the cardiac metabolic level to one or morepredetermined thresholds defining a normal range of cardiac metaboliclevel. An abnormal condition is detected when the cardiac metaboliclevel is outside of the normal range of cardiac metabolic level.

In one embodiment, sensor 212 includes an implantable impedance sensorto measure pulmonary impedance, or impedance of a portion of thethoracic cavity. Event detector 213 detects an abnormal condition whenthe impedance is out of its normal range. For example, pulmonary edema,i.e., fluid retention in the lungs resulting from the decreased cardiacoutput, increases pulmonary or thoracic impedance. In one specificembodiment, event detector 213 produces a signal when the pulmonary orthoracic impedance exceeds a predetermined threshold impedance. In oneembodiment, the impedance sensor is a respiratory sensor that senses thepatient's minute ventilation. An example of an impedance sensor sensingminute ventilation is discussed in U.S. Pat. No. 6,459,929, “IMPLANTABLECARDIAC RHYTHM MANAGEMENT DEVICE FOR ASSESSING STATUS OF CHF PATIENTS,”assigned to Cardiac Pacemakers, Inc., which is incorporated herein byreference in its entirety.

In one embodiment, sensor 212 includes a pressure sensor. Abnormalconditions including arrhythmias and heart failure cause pressures invarious portions of the cardiovascular system to deviate from theirnormal ranges. Event detector 213 detects the abnormal condition when apressure is outside of its normal range. In one specific embodiment,event detector 213 includes a systolic dysfunction detector to detect anabnormal condition related to pressure during the systolic phase of acardiac cycle. In another specific embodiment, event detector 213includes a diastolic dysfunction detector to detect an abnormalcondition related to pressure during the diastolic phase of a cardiaccycle. Examples of the pressure sensor include but are not limited to aleft atrial (LA) pressure sensor, a left ventricular (LV) pressuresensor, an artery pressure sensor, and a pulmonary artery pressuresensor. Pulmonary edema results in elevated LA and pulmonary arterialpressures. A deteriorated LV results in decreased LV and arterialpressures. In various embodiments, event detector 213 detects anabnormal condition when the LA pressure exceeds a predeterminedthreshold LA pressure level, when the pulmonary arterial pressureexceeds a predetermined threshold pulmonary arterial pressure level,when the LV pressure falls below a predetermined threshold LV pressurelevel, and/or when the arterial pressure falls below a predeterminedthreshold LV pressure level. In other embodiments, event detector 213derives a parameter from one of these pressures, such as a rate ofchange of a pressure, and produces a signal when the parameter deviatesfrom its normal range. In one embodiment, the LV pressure sensor sensesthe LV pressure indirectly, by sensing a signal having known orpredictable relationships with the LV pressure during all or a portionof the cardiac cycle. Examples of such a signal include but are notlimited to an LA pressure and a coronary vein pressure. One specificexample of measuring the LV pressure using a coronary vein pressuresensor is discussed in U.S. patent application Ser. No. 10/038,936,“METHOD AND APPARATUS FOR MEASURING LEFT VENTRICULAR PRESSURE,” filed onJan. 4, 2002, assigned to Cardiac Pacemakers, Inc., which is herebyincorporated by reference in its entirety.

In one embodiment, sensor 212 includes a cardiac output or stroke volumesensor. Examples of stroke volume sensing are discussed in U.S. Pat. No.4,686,987, “BIOMEDICAL METHOD AND APPARATUS FOR CONTROLLING THEADMINISTRATION OF THERAPY TO A PATIENT IN RESPONSE TO CHANGES INPHYSIOLOGIC DEMAND,” and U.S. Pat. No. 5,284,136, “DUAL INDIFFERENTELECTRODE PACEMAKER,” both assigned to Cardiac Pacemakers, Inc., whichare incorporated herein by reference in their entirety. Event detector213 detects the abnormal condition when the stroke volume falls below apredetermined threshold level.

In one embodiment, sensor 212 includes a neural activity sensor todetect activities of the sympathetic nerve and/or the parasympatheticnerve. A significant decrease in cardiac output immediately stimulatessympathetic and/or the parasympathetic activities, as the autonomicnervous system attempts to compensate for deteriorated cardiac function.In one specific embodiment, a neural activity sensor includes aneurohormone sensor to sense a neurohormone level. Event detector 213detects the abnormal condition when the hormone level exceeds apredetermined threshold level. In another specific embodiment, a neuralactivity sensor includes an action potential recorder to sense theelectrical activities in the sympathetic nerve and/or theparasympathetic nerve. Event detector 213 detects an abnormal conditionwhen the frequency of the electrical activities in the sympatheticand/or the parasympathetic nerves exceed a predetermined thresholdlevel. Examples of direct and indirect neural activity sensing arediscussed in U.S. Pat. No. 5,042,497, “ARRHYTHMIA PREDICTION ANDPREVENTION FOR IMPLANTED DEVICES,” assigned to Cardiac Pacemakers, Inc.,which is hereby incorporated by reference in its entirety.

In one embodiment, sensor 212 includes a heart rate variabilitydetector. Patients suffering acute decompensated heart failure exhibitabnormally low heart rate variability. An example of detecting the heartrate variability is discussed in U.S. Pat. No. 5,603,331, “DATA LOGGINGSYSTEM FOR IMPLANTABLE CARDIAC DEVICE,” assigned to Cardiac Pacemakers,Inc., which is incorporated herein by reference in their entirety. Eventdetector 213 detects an abnormal condition when the heart ratevariability falls below a predetermined threshold level.

In one embodiment, sensor 212 includes a renal function sensor. Acutedecompensated heart failure results in peripheral edema primarilybecause of fluid retention of the kidneys that follows the reduction incardiac output. The fluid retention is associated with reduced renaloutput, decreased glomerular filtration, and formation of angiotensin.Thus, in one specific embodiment, a renal function sensor includes arenal output sensor to sense a signal indicative of the renal output.Event detector 213 detects an abnormal condition when the sensed renaloutput falls below a predetermined threshold. In another specificembodiment, a renal function sensor includes a filtration rate sensor tosense a signal indicative of the glomerular filtration rate. Eventdetector 213 detects an abnormal condition when the sensed glomerularfiltration rate falls below a predetermined threshold. In yet anotherspecific embodiment, a renal function sensor includes a chemical sensorto sense a signal indicative of angiotensin II levels. Event detector213 detects the abnormal condition when the sensed angiotensin II levelsexceed a predetermined threshold level.

In one embodiment, sensor 212 includes an acoustic sensor such as aheart sound sensor and/or a respiratory sound sensor. Arrhythmias and/orheart failure cause abnormal cardiac and pulmonary activity patterns andhence, deviation of heart sounds and respiratory sounds from theirnormal ranges of pattern and/or amplitude. Event detector 213 detects anabnormal condition when the heart sound or respiratory sound is out ofits normal range. For example, detection of abnormal third heard sound(S3) amplitude is known to indicate heart failure. In one specificembodiment, event detector 213 detects an abnormal condition when the S3amplitude exceeds a predetermined threshold level.

In one embodiment, sensor 212 includes a remodeling sensor to sense asignal indicative a degree of myocardial remodeling. In one specificembodiment, the remodeling sensor includes two or more piezoelectriccrystals incorporated in one or more leads of lead system 108 to sense asize of an injured myocardial region such as an infarct region. The sizeof the injured myocardial region is estimated based on spatialinformation sensed by the crystals and averaged over a predeterminedperiod of time. In one embodiment, a substantial degree of change in thesize of the injured region indicates a need to start, stop, or adjustthe combined electrical and agent therapies. In another specificembodiment, sensor 212 includes a hypertrophic sensor to sense a signalindicative of a degree of myocardial hypertrophy, which indicates theprogress of the remodeling process. In another specific embodiment,sensor 212 includes a chemical sensor to sense the change in expressionor concentration of Endothelin-1 (ET-1), BNP, or p38MAPK, which areknown to change during hypertrophy response. In a further embodiment,sensor processing circuit 215 includes an event detector to detect anabnormal condition when the degree of myocardial remodeling exceeds apredetermined threshold. The degree of myocardial remodeling isrepresented by one or more of the degree of change in the size of theinjured region, the degree of myocardial hypertrophy, and the degree ofthe change in expression or concentration of Endothelin-1 (ET-1), BNP,or p38MAPK.

Embodiments of sensor 212 and event detector 213 are discussed in thisdocument by way of example, but not by way of limitation. Other methodsand sensors for directly or indirectly detecting an abnormal conditiontreatable by the gene/protein delivery may be employed with gene/proteindelivery system 100.

Implantable CRM device 110 includes a hermetically sealed metal can tohouse at least portion of the electronics of the device. In oneembodiment, sensor 212 resides within the metal can. In anotherembodiment, sensor 212 is outside of the metal can. In one embodiment,sensor 212 is incorporated into a lead system 108.

FIG. 3 is a block diagram showing a further embodiment of the circuit ofportions of system 100 including implantable CRM device 110, lead system108, gene/protein delivery device 130, and external system 155.Implantable CRM device 110 as shown in FIG. 3 includes pacing anddefibrillation capabilities. In addition to gene/protein delivery,examples of therapies delivered by implantable CRM device 110 include,but are not limited to, bradyarrhythmia pacing, anti-tachyarrhythmiapacing, atrial and/or ventricular cardioversion/defibrillation, CRT,RCT, and drug delivery. However, the pacing and defibrillationcapabilities are not necessary for system 100 to perform gene/proteindelivery, and hence, may be excluded from implantable CRM device 110. Inother words, implantable CRM device 110 can be an implantable pacemakerand/or defibrillator with additional functions including control ofgene/protein delivery, or it can be a dedicated implantable gene/proteindelivery processor or controller.

In one embodiment, implantable CRM device 110 includes sensor 212, eventdetector 213, implant controller 214, pacing circuit 320, defibrillationcircuit 324, and implant telemetry module 316. Pacing circuit 320delivers pacing pulses to one or more cardiac regions as controlled byimplant controller 214. Defibrillation circuit 324 deliverscardioversion or defibrillation shocks to one or more cardiac regions ascontrolled by implant controller 214. Sensor 212 senses a physiologicalsignal indicative of a condition treatable with gene/protein delivery,and event detector 213 detects that condition, as discussed above withreference to FIG. 2. In one specific embodiment, in which implantableCRM device 110 provides for CRT and RCT pacing as well asdefibrillation, implant controller 214 includes gene/protein deliverycontrol module 215, CRT control module 321, RCT control module 322,defibrillation control module 323, and command receiver 326.Gene/protein delivery control module 215 generates a gene/proteindelivery control signal in response to a condition detected by eventdetector 213 or a gene/protein delivery command received by commandreceiver 326. Command receiver 326 receives a gene/protein deliverycommand from external system 155 via telemetry link 140. CRT controlmodule 321 controls the delivery of pacing pulses from pacing circuit320 by executing a CRT algorithm. RCT control module 322 controls thedelivery of pacing pulses from pacing circuit 320 by executing a RCTalgorithm. Defibrillation control module 323 controls the delivery ofcardioversion/defibrillation shocks from defibrillation circuit 324 whena tachyarrhythmic condition is detected. In one embodiment,defibrillation control module 323 includes an atrial defibrillationcontrol module to control the delivery of cardioversion/defibrillationshocks to one or more of the atria. In one embodiment, defibrillationcontrol module 323 includes a ventricular defibrillation control moduleto control the delivery of cardioversion/defibrillation shocks to one ormore of the ventricles.

Lead system 108 includes one or more gene/protein delivery controlleads, referenced as lead system 108A, and pacing leads, defibrillationleads, pacing-defibrillation leads, or any combination of such leads,referenced as lead system 108B. Lead system 108A allows gene/proteindelivery control module 215 to control implantable gene/protein deliverydevice 130. Lead system 108B allows sensing of electrical signals fromvarious regions of heart 101 and/or delivery of pacing pulses and/ordefibrillation shocks to various regions of heart 101. The variousregions of heart 101 includes regions within or about the right atrium(RA), left atrium (LA), right ventricle (RV), and left ventricle (LV).In one embodiment, lead system 108B includes one or more transvenousleads each having at least one sensing-pacing or defibrillationelectrode disposed within heart 101. In one embodiment, lead system 108Bincludes one or more epicardial leads each having at least onesensing-pacing or defibrillation electrode disposed on heart 101. In oneembodiment, lead system 108B includes at least one atrial defibrillationelectrode disposed in or about one or both of the atria to allow atrialdefibrillation. In one embodiment, lead system 108B includes at leastone ventricular defibrillation electrode disposed in or about one orboth of the ventricles to allow ventricular defibrillation. In oneembodiment, sensor 212 includes at least portions of lead system 108A or108B. In another embodiment, sensor 212 is incorporated into lead system108A or 108B.

External system 155 includes external telemetry module 352, externaluser input device 354, presentation device 356, and external controller358. These system components distribute in one or more of externaldevice 150, network 160, or remote device 170, depending on design andmedical considerations. User input device 354 receives commands and/orparameters from the user and/or the patient to control deliveries oftherapy, including gene/protein delivery. Presentation device 356displays or otherwise presents signals acquired and/or conditionsdetected by implantable CRM device 110. External controller 358 controlsthe operation of external system 155. In one embodiment, externalcontroller 358 further provides automatic control of operations of animplantable CRM device 110. In one embodiment, user input device 352receives the gene/protein delivery command entered by the user based onobservations of the signals and/or conditions presented by presentationdevice 356. In another embodiment, user input device 352 receives thegene/protein delivery command entered by a patient when the patientphysically senses a symptom indicative of an immediate need for thegene/protein therapy, or entered by a person near the patient whoobserves a symptom indicative of the immediate need for the gene/proteintherapy. In a further embodiment, external controller 358 automaticallyanalyzes the signals acquired and/or abnormal conditions detected byimplantable CRM device 110, and generates a gene/protein deliverycommand when deemed necessary as a result of the analysis.

Telemetry link 140 is a wireless bidirectional data transmission linksupported by implant telemetry module 316 and external telemetry module352. In one embodiment, telemetry link 140 is an inductive couple formedwhen two coils—one connected to implant telemetry module 316 and theother connected to external telemetry module 352—are placed near eachother. In another embodiment, telemetry link 140 is a far-fieldradio-frequency telemetry link allowing implantable CRM device 110 andexternal system 155 to communicate over a telemetry range that is atleast ten feet.

Implantable Iontophoresis Gene/Protein Delivery Device

The system of the invention includes an implantable iontophoresis geneand/or protein delivery device coupled to an implantable pulsegenerator. The implantable iontophoresis gene/protein delivery deviceincludes a polymer matrix and isolated nucleic acid which encodes atleast one gene product, isolated nucleic acid which binds at least oneselected mRNA, and/or isolated protein, or any combination thereof. Theisolated nucleic acid or protein is selected at the discretion of thepractitioner on the basis of a correlation of the sequence with aparticular condition, e.g., a correlation with beneficially altering thecondition. Examples of selected genes and proteins are provided below.

Exemplary Gene(s) and/or Protein(s)

For iontophoresis techniques to be used, the molecule embedded in orapplied to the polymer matrix should have specific characteristics.Ideally, the molecule should have an ionic nature or have other ionicmolecules bound to the molecule to promote the iontophoretic movement ortransport of that molecule from the polymer matrix. Gene(s) and/orprotein(s) suitable for the implantable iontophoresis gene/proteindelivery device of the invention include those useful to treat, inhibit(reduce) or eliminate one or more symptoms associated with a particularcondition.

In one embodiment, where an increase in a particular gene product isindicated to treat, inhibit or eliminate one or more symptoms associatedwith a particular condition, at least a portion of an open reading frameencoding the gene product in sense orientation is operably linked totranscriptional control elements, for instance, a heterologoustranscriptional control element, optionally including a tissue-specificcontrol element, to form an expression cassette. For example, in oneembodiment, the expression cassette includes an open reading frame forconnexin 43 operably linked to a cardiac-specific promoter. In anotherembodiment, the expression cassette includes an open reading frame for amammalian ion channel protein which is operably linked to a viralpromoter.

In another embodiment, where a decrease in a particular gene product isindicated to treat, inhibit or eliminate one or more symptoms associatedwith a particular condition, at least a portion of an open reading framefor that gene product in antisense orientation is operably linked totranscriptional control elements, for instance, a heterologoustranscriptional control element, optionally including a tissue-specificcontrol element, to form an expression cassette. Alternatively,antisense nucleic acid is not present in an expression cassette, i.e.,not operably linked to a transcriptional control element, e.g., apromoter.

For purposes of the present invention, control elements, such asmuscle-specific and inducible promoters, enhancers and the like, will beof particular use. Such control elements include, but are not limitedto, those derived from the actin and myosin gene families, such as fromthe myoD gene family (Weintraub et al., Science, 251, 761 (1991)); themyocyte-specific enhancer binding factor MEF-2 (Cserjesi and Olson, Mol.Cell Biol., 11, 4854 (1991)); control elements derived from the humanskeletal actin gene (Muscat et al., Mol. Cell Bio., 7, 4089 (1987)) andthe cardiac actin gene; muscle creatine kinase sequence elements(Johnson et al., Mol. Cell Biol., 9, 3393 (1989)) and the murinecreatine kinase enhancer (mCK) element; control elements derived fromthe skeletal fast-twitch troponin C gene, the slow-twitch cardiactroponin C gene and the slow-twitch troponin I gene; hypoxia-induciblenuclear factors (Semenza et al., Proc. Natl. Acad. Sci. USA, 88, 5680(1991); Semenza et al., J. Biol. Chem., 269, 23757); steroid-inducibleelements and promoters, such as the glucocorticoid response element(GRE) (Mader and White, Proc. Natl. Acad. Sci. USA, 90, 5603 (1993));the fusion consensus element for RU486 induction; and elements thatprovide for tetracycline regulated gene expression (Dhawan et al.,Somat. Cell. Mol. Genet., 21, 233 (1995); Shockett et al., Proc. Natl.Acad. Sci. USA, 92, 6522 (1995)).

In one embodiment, cardiac cell restricted promoters will be ofparticular use. Cardiac specific promoters include, but are not limitedto, promoters from the following genes: a α-myosin heavy chain gene,e.g., a ventricular α-myosin heavy chain gene, β-myosin heavy chaingene, e.g., a ventricular β-myosin heavy chain gene, myosin light chain2v gene, e.g., a ventricular myosin light chain 2 gene, myosin lightchain 2a gene, e.g., a ventricular myosin light chain 2 gene,cardiomyocyte-restricted cardiac ankyrin repeat protein (CARP) gene,cardiac α-actin gene, cardiac m2 muscarinic acetylcholine gene, ANPgene, BNP gene, cardiac troponin C gene, cardiac troponin I gene,cardiac troponin T gene, cardiac sarcoplasmic reticulum Ca-ATPase gene,skeletal α-actin gene, as well as an artificial cardiac cell-specificpromoter.

Further, chamber-specific promoters or enhancers may also be employed,e.g., for atrial-specific expression, the quail slow myosin chain type 3(MyHC3) or ANP promoter, or the cGATA-6 enhancer, may be employed. Forventricle-specific expression, the iroquois homeobox gene may beemployed. Examples of ventricular myocyte-specific promoters include aventricular myosin light chain 2 promoter and a ventricular myosin heavychain promoter.

Other sources for promoters and/or enhancers are promoters and enhancersfrom the Csx/NKX 2.5 gene, titin gene, α-actinin gene, myomesin gene, Mprotein gene, cardiac troponin T gene, RyR2 gene, Cx40 gene, and Cx43gene, as well as genes which bind Mef2, dHAND, GATA, CarG, E-box,Csx/NKX 2.5, or TGF-beta, or a combination thereof.

Tissue-specific enhancers may also be employed. For instance, apreferred atrial-specific enhancer is the cGATA-6 enhancer. In otherembodiments, the enhancer is not tissue-specific.

In yet other embodiments, the promoter is a non-muscle, non-cardiactissue-specific promoter.

Nevertheless, other promoters and/or enhancers which are not specificfor certain tissue or cells, e.g., a viral promoter such a one from anadenovirus, adeno-associated virus, retrovirus, herpesvirus orlentivirus, may be employed in the expression cassettes and methods ofthe invention. A preferred heterologous constitutive promoter is a CMVpromoter which also includes an enhancer.

Preferably, the gene is also operably linked to a polyadenylationsignal.

In one embodiment, the condition is a cardiovascular conditionincluding, but not limited to, atrial fibrillation, ischemia,ventricular tachycardia, bradycardia, hyperplasia, or heart failure.Genes and corresponding proteins useful in the system and methods forcardiovascular conditions include, but are not limited to, a connexingene, an atrial-specific ion channel protein gene, e.g., a gene productassociated with I_(f), a non-specific ion channel protein gene, e.g., agene product associated with I_(K), a gene product which regulates gapjunctions, a gene product which alters conduction in the myocardium, agene product which encodes a regulatory protein which blocks ion channelprotein synthesis or activity, a gene product which upregulates ionchannel protein synthesis or activity, a gene product whichdownregulates at least one ion channel protein, or a gene product whichalters ion channel kinetics or voltage.

Thus, useful genes and corresponding proteins include genes for ionchannels, including K⁺, Na⁺, Ca⁺ and voltage activated channels, andpreferably ion channels expressed in cardiac tissue, including, but notlimited to, HCN (for I_(f)), Kir 2.1 (for I_(K1)), Kir 3.1/3.4 (forI_(KACh)), ERG (α subunit for I_(Kr)), MiRP1 (modulates I_(Kr), I_(f)and I_(to)), KvLQT1 (α subunit for I_(KS)), MinK (β subunit for I_(KS)),Kv4.2/4.3 (α subunit for I_(to)), Kv1.4 (α subunit for I_(to)), KChIP2(β subunit for I_(to)), Kv1.5 (for I_(Kur)), Cav1.2 (I_(CaL)), Cav1.3(I_(CaV)), Cav3.1 (I_(Ca)), Nav1.5 (I_(Na)), and connexin 40, connexin43, and connexin 45 (I_(GJ)) (see Schram et al., Circ. Res., 90:939(2002)), the disclosure of which is specifically incorporated byreference herein), NCX, e.g., NCX1, NCX2 and NCX3, Kir 6.1, Kir6.2,Kv1.7, Kv4.2, Kv4.3, Kv4.1 as well as Na ion channels such as SCN5A.Other genes useful in the system and methods of the invention include,but are not limited to, Galphai2 subunit, neurotensin, calmodulin,calmodulin-dependent kinase, ATF3, calcitonin gene related peptide(CGRP), NOS, e.g., nNOS, iNOS and eNOS, Nkx 2.5, dystrophin, tafazzin,cardiac actin, desmin, lamin A/C, delta sarcoglycan, cardiac β myosinheavy chain, and cardiac tropin C, β-adrenergic receptors, inhibitoryguanine nucleotide protein, GPCR kinases, VEGF, placental growth factor,ACE(2), Cox2, for calcium regulation, calmodulin, CaMKII, RyR (ryanodinereceptor), SERCA, calcium ATPase (CSR), phospholamban (PLB),calcineurin, and FK506 binding protein, Lbx1, AT1A receptor, AT2,p27(KIP1), calcineurin, angiotensin IT, and HSP. To prevent, inhibit ortreat heart failure, the following genes/proteins may be useful:calmodulin, CaMKII, RyR (ryanodine receptor), SERCA, calcium ATPase(CSR), phospholamban (PLB), calcineurin, and FK506 binding protein. Toprevent, inhibit or treat hyperplasia, the following genes/proteins maybe useful: Lbx1, AT1A receptor, AT2, p27(KIP1), calcineurin, angiotensinII, and HSP. To prevent, inhibit or treat ischemia, the followinggenes/proteins may be useful: CGRP, ATF3, placental growth factor andCox2. To increase contractility, the following genes/proteins may beuseful: neurotensin and ACE(2).

Polymer Matrix

The polymer matrix may be formed of any physiologically compatiblematerial which generally retains isolated nucleic acid and/or protein(which are charged molecules) or optionally other agents including othertherapeutic agents under physiological conditions for a sustained periodof time, e.g., for months or years, in the absence of an electricalfield. The polymer matrix extrudes (releases) isolated nucleic acid orprotein from the implantable iontophoresis gene or protein deliverydevice in response to an electric field created by an electrical signal.The electric signal is generated in response to the detection of aphysiological signal associated with a condition, e.g., a cardiovascularcondition.

The isolated nucleic acid and/or protein or optional other agent(s) maybe introduced to a solution of monomers prior to polymerization or tothe polymer matrix, e.g., dissolved in a solvent (e.g., water,propylene, glycol, etc.) and the resulting solution can be incorporatedinto the polymer matrix material. Once the isolated nucleic acid and/orprotein is embedded in or applied to a polymer matrix, the resultinggene/protein delivery device can be coupled to an implantable pulsegenerator. Alternatively, the polymer matrix may be first coupled to theimplantable pulse generator and then the isolated nucleic acid and/orprotein embedded in or applied thereto, either passively or actively(through, for example, such methods as iontophoresis). Upon delivery ofan electric field, the isolated nucleic acid and/or protein or optionalother agent(s) is released from the matrix at a rate which is greaterthan the rate of release in the absence of the electric field. Inparticular, the isolated nucleic acid and/or protein in an implantediontophoresis gene/protein delivery device is released to adjacent cellsor tissue or the vessel lumen in response to an electric field generatedby the implantable pulse generator, which release is in an amountproportional to the applied electric field. Once the electric signal isstopped, the genes and/or proteins are no longer released or released ata rate which is significantly reduced relative to the rate of release inthe presence of the electric field. Thus, the delivery of the gene(s)and/or protein(s) is transient (temporary) and may be spatiallycontrolled by the direction of the electric field and placement of thedevice.

The matrix materials will preferably be physiologically inert andcapable of retaining the charged molecule to be delivered. Matrixmaterials which may be used include: polyacetic or polyglycolic acid andderivatives thereof, polyorthoesters, polyesters, polyurethanes,polyamino acids such as polylysine, lactic/glycolic acid copolymers,polyanhydrides and ion exchange resins such as sulfonatedpolytetrafluorethylene, or combinations thereof.

Additionally, it is possible to construct the matrices from naturalproteins or materials which are crosslinked using a crosslinking agentsuch as 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide hydrochloride.Such natural materials are those such as albumin, collagen, fibrin,gelatin, keratin, potato starch hydrolyzed for use in electrophoresis,and agar-agar (agarose). Synthetic electrophoretic matrices are alsosuitable including polyacrylamide, acrylamide/bis-acrylamide mixtures,cellulose acetate, glyoxyl agarose, and Sephadex™ (Pharmacia FineChemicals, Inc.) suitable for use in isoelectrofocusing. It is alsopossible to use combinations of such matrices, such as the combinationof polyacrylamide and agarose, in order to fabricate the cathodic matrixof the invention.

In one embodiment, the polymer matrix may include liposomes, a hydrogel,cyclodextrins, biodegradable nanocapsules or microspheres. Thus, polymermatrix includes synthetic polymers in the form of hydrogels or otherporous materials, e.g., nucleic acid and/or protein permeableconfigurations or morphologies, such as polyvinyl alcohol,polyvinylpyrrolidone and polyacrylamide, polyethylene oxide,poly(2-hydroxyethyl methacrylate); natural polymers such as gums andstarches; synthetic elastomers such as silicone rubber, polyurethanerubber; and natural rubbers, and includepoly[α(4-aminobutyl)]-1-glycolic acid, polyethylene oxide (Roy et al.,Mol. Ther., 7:401 (2003)), poly orthoesters (Heller et al., Adv. DrugDelivery Rev., 54:1015 (2002)), silk-elastin-like polymers (Megeld etal., Pharma. Res., 19:954 (2002)), alginate (Wee et al., Adv. DrugDeliv. Rev., 31:267 (1998)), EVAc (poly(ethylene-co-vinyl acetate),microspheres such as poly (D,L-lactide-co-glycolide)copolymer andpoly(L-lactide), poly(N-isopropylacrylamide)-b-poly(D,L-lactide), a soymatrix such as one cross-linked with glyoxal and reinforced with abioactive filler, e.g., hydroxylapatite,poly(epsilon-caprolactone)-poly(ethylene glycol)copolymers,poly(acryloyl hydroxyethyl)starch, polylysine-polyethylene glycol, anagarose hydrogel, or a lipid microtubule-hydrogel.

In one embodiment, the nucleic acid or protein is embedded in or appliedto a polymer matrix, e.g., a nonionic or ionic biodegradable ornonbiodegradable matrix, including but not limited to hydrogels ofpoloxamers, polyacrylamide, poly(2-hydroxyethyl methacrylate),carboxyvinyl-polymers (e.g., Carbopol 934,Goodrich Chemical Co.),cellulose derivatives, e.g., methylcellulose and hydroxypropylcellulose, polyvinyl pyrrolidone or polyvinyl alcohols.

In another embodiment, the biocompatible polymeric materials aresynthetic, nonbiodegradable polymers such as polyurethanes,polydimethylsiloxanes (silicone rubbers), ethylene vinyl acetatecopolymer (EVA), poly methylmethacrylate, polyamides, polycarbonates,polyesters, polyethylene, polypropylenes, polystyrenes, polyvinylchloride, polyvinyl alcohols, polytetrafluoroethylene, or cellulosederivatives such as cellulose acetate.

In alternative embodiments, the biocompatible polymeric material is abiodegradable polymeric such as collagen, fibrin,polylactic-polyglycolic acid, or a polyanhydride. Other examplesinclude, without limitation, any biocompatible polymer, whetherhydrophilic, hydrophobic, or amphiphilic, such as ethylene vinyl acetatecopolymer (EVA), polymethyl methacrylate, polyamides, polycarbonates,polyesters, polyethylene, polypropylenes, polystyrenes, polyvinylchloride, polytetrafluoroethylene, or cellulose derivatives such ascellulose acetate. In an alternative embodiment, a biologically derivedpolymer, such as protein collagen, fibrin, polylactic-polyglycolic acid,or a polyanhydride, is a suitable polymeric matrix material.

The above examples are provided for reference only, and the range ofsuitable polymer matrix materials should not be construed as limited tothose materials listed above. The polymer matrix material can behydrophilic, hydrophobic, or amphiphilic, provided it meets the physicalcharacteristics described above. See also U.S. Pat. No. 5,087,243 andAvitall et al., Circ., 85:1582 (1992). The polymer matrix preferablystabilizes the gene(s) and/or protein(s) and other optional agents inthe polymer matrix.

A polymer matrix may also be present in a selectively semipermeablemembrane such as a dialysis membrane, nylon or polysulfoxy. In oneembodiment, the semipermeable membrane is not biodegradable.

In another embodiment, it is possible to fabricate multiple-layeredcathodic reservoirs. Such multiple-layered reservoirs will findusefulness in certain embodiments in which there is desire to haveadditional control over the rate at which the charged substance iselectrophoresed from the matrix. Thus, where it is desired to preventdiffusion of an anionic molecule chiefly occurring at the surface of thereservoir in contact with the target tissue, a relativelystrongly-cationic matrix material may be used to cap a relativelyweakly-cationic matrix material. This multiple-layered matrix embodimentmay be preferentially utilized where a relatively more toxic, but moreefficacious molecule is to be initially utilized to lower the immediatepost-implantation stimulation threshold. However, and particularly inpatients with a history of cardiac arrhythmia or fibrillation, it may beuseful to charge a second layer with an anti-arrhythmic orantifibrillation drug, which drug is delivered only upon the necessaryphysiological demand. Similar combinations may be made in patientscombinations may be made in patients with histories of cardiac arrest,where thyroid hormone therapy may be desired.

When a multiple-layered matrix is used, it is also possible tosequentially deliver a gradually declining (or increasing, or cyclical)concentration of the molecule. In such an embodiment, the distal mostmatrix reservoir may contain a first lower dose of the molecule,followed by a next most distal matrix with a concentration of themolecule higher than the first, and so on.

Methods of Using the Implantable Systems

The implantable systems of the invention which include an implantablepulse generator and an implantable iontophoresis gene/protein deliverydevice may coupled to other implantable devices, e.g., a stent, shunt,indwelling catheter, lead or epicardial patch, or minimally invasivedevices, e.g., a transdermal patch. Such combined devices may beintroduced to vessels, e.g., a vein, or other body lumens. In oneembodiment, an implantable system of the invention is introduced to amammalian heart, e.g., to one or both atria. For example, a mammalhaving or at risk of having atrial fibrillation is provided with asystem which includes an implantable pulse generator and an implantableiontophoresis gene/protein delivery device, which system may be coupledto the atria of the heart. Upon sensing a physiological signalindicative of atrial fibrillation, the implant controller in theimplantable pulse generator produces an electric signal which results inan electric field. The isolated nucleic acid and/or protein in theimplantable iontophoresis gene/protein delivery device is released toadjacent cells or tissue or the vessel lumen in response to the electricfield in an amount proportional to the applied electric field. Thedosage ranges for the gene(s)/protein(s) are those large enough toproduce the desired effect in which the symptoms of the condition areameliorated. The dosage should not be so large as to cause adverse sideeffects. Generally, nucleic acid dosages include from about 0.001 toabout 500 μg, e.g., from about 0.01 μg to about 100 μg, and for proteindosages, from about 1 ng to about 10 mg, e.g., from about 1 μg to about1 mg. Generally, the dosage will vary with the age, condition, sex andextent of the disease in the patient and can be determined by one ofskill in the art. Once the electric signal is stopped, the genes and/orproteins are no longer released or released at a rate which issignificantly reduced relative to the rate of release in the presence ofthe electric field. Thus, the delivery of the gene(s) and/or protein(s)is transient (temporary) and may be spatially controlled by thedirection of the electric field and placement of the device.

In one embodiment, where the heart tissue around the entire periphery ofthe heart is to receive the nucleic acid/protein, it is administered tothe pericardial sac. In another embodiment, nucleic acid/protein whichis present in a hydrogel can be percutaneously applied to the surface ofthe heart applied to the heart muscle. However, it will be appreciatedthat the strength and/or distribution of the electric field can becontrolled such that a larger or smaller area of the heart tissue can betreated.

The frequency range for iontophoresis begins at 0 Hz (dc) and increasesto a maximum of about 20 MHz, with the preferred range lying between2-15 kHz. In one embodiment, the electric field is an ac field with a dcoffset. It will be understood that the frequency can be varied withinthese ranges to maximize the rate of iontophoretic transfer for a givendrug used in the catheters of the present invention. Selecting afrequency range that is significantly higher then the intrinsic heartrate reduces the risk of inducing an arrhythmia.

The apparatus and system of the invention may be employed with othertherapies, e.g., electrical therapies such as pacing, CRT, RCT anddefibrillation, drug therapies, and/or non-localized gene therapy, e.g.,which results in integrated genes. Other therapies may include but arenot limited to treatment with growth factors and/or angiogenic factors,or drugs such as beta-adrenergic blockers, e.g., propranolol, calciumchannel blockers, e.g., verapamil, angiotensin converting enzymeinhibtors, e.g., captopril, angiotension II receptor blockers, e.g.,losartan, alpha adrenergic blockers, e.g., doxazosin, or hypotensiveagents, e.g., reserpine, antilipemic agents, e.g., simvastatin,vasodilating agents, e.g., amyl nitrite, carvedilol, adenosine, digoxin,ibutilide, lidocaine, neseritide and the like.

All publications, patents and patent applications are incorporatedherein by reference. While in the foregoing specification, thisinvention has been described in relation to certain preferredembodiments thereof, and many details have been set forth for purposesof illustration, it will be apparent to those skilled in the art thatthe invention is susceptible to additional embodiments and that certainof the details herein may be varied considerably without departing fromthe basic principles of the invention.

1. A system, comprising: an implantable pulse generator including: asensor to sense a physiological signal indicative of a predeterminedcardiac condition; an event detector, coupled to the sensor, to detectthe predetermined cardiac condition from the physiological signal; animplant telemetry module to receive an external command transmitted tothe implantable pulse generator; and an implant controller coupled tothe event detector and the implant telemetry module, the implantcontroller including a gene or protein delivery control moduleconfigured to produce an electrical signal to control iontophoretic geneor protein delivery in response to the predetermined cardiac conditionand the external command; an implantable lead system including one ormore leads, the lead system configured to transmit the electricalsignal; and an implantable gene or protein delivery device electricallywired to the implantable pulse generator through the implantable leadsystem, the implantable gene or protein delivery device configured toreceive the electrical signal and including a polymer matrix andisolated nucleic acid which encodes at least one gene product or bindsat least one selected mRNA, or isolated protein, the nucleic acid orprotein contained in the polymer matrix and released from theimplantable gene or protein delivery device in response to an electricfield applied to the polymer matrix, the electric field created by theelectrical signal.
 2. The system of claim 1, wherein the sensorcomprises an electrogram sensing circuit, and the event detectorcomprises an arrhythmia detector.
 3. The system of claim 2, wherein thearrhythmia detector comprises one or more of a bradycardia detector, atachycardia detector, and a fibrillation detector.
 4. The system ofclaim 3, wherein the fibrillation detector comprises an atrialfibrillation detector.
 5. The system of claim 3, wherein thefibrillation detector comprises a ventricular fibrillation detector. 6.The system of claim 1, wherein the sensor comprises a sensor sensing anphysiological signal indicative of ischemia, and the event detectorcomprises an ischemia detector.
 7. The system of claim 1, wherein thesensor comprises a metabolic sensor adapted to sense a signal indicativeof a cardiac metabolic level.
 8. The system of claim 7, wherein thesensor comprises at least one of a pH sensor, an oxygen pressure (PO₂)sensor, a carbon dioxide pressure (PCO₂) sensor, a glucose sensor, acreatine sensor, a C-creative protein sensor, a creatine kinase sensor,and a creatine kinase-MB sensor.
 9. The system of claim 1, wherein thesensor comprises an impedance sensor to sense tissue impedance.
 10. Thesystem of claim 9, wherein the impedance sensor comprises a pulmonaryimpedance sensor.
 11. The system of claim 10, wherein the impedancesensor comprises a respiratory sensor.
 12. The system of claim 1,wherein the sensor comprises a pressure sensor to sense a pressure in acardiovascular system.
 13. The system of claim 12, wherein the pressuresensor comprises at least one of a left atrial pressure sensor, a leftventricular pressure sensor, an artery pressure sensor, and a pulmonaryarterial pressure sensor.
 14. The system of claim 13, wherein the eventdetector comprises a systolic dysfunction detector.
 15. The system ofclaim 13, wherein the event detector comprises a diastolic dysfunctiondetector.
 16. The system of claim 1, wherein the sensor comprises astroke volume sensor.
 17. The system of claim 1, wherein the sensorcomprises a neural activity sensor.
 18. The system of claim 17, whereinthe neural activity sensor comprises a neurohormone sensor to sense aneurohormone level.
 19. The system of claim 17, wherein the neuralactivity sensor comprises an action potential recorder to sense neuralelectrical activities.
 20. The system of claim 1, wherein the sensorcomprises a heart rate variability detector.
 21. The system of claim 1,wherein the sensor comprises a renal function sensor.
 22. The system ofclaim 21, wherein the renal function sensor comprises at least one of arenal output sensor, a filtration rate sensor, and an angiotensin IIlevel sensor.
 23. The system of claim 1, wherein the sensor comprises anacoustic sensor adapted to sense at least one of heart sounds andrespiratory sounds.
 24. The system of claim 23, wherein the eventdetector to detect the predetermined cardiac condition when third hearsound (S3) amplitude exceeds a predetermined threshold.
 25. The systemof claim 1, wherein the sensor comprises a remodeling sensor to sense asignal indicative a degree of myocardial remodeling.
 26. The system ofclaim 25, wherein the remodeling sensor comprises two or morepiezoelectric crystals to sense a size of an injured myocardial region.27. The system of claim 1, wherein the implantable gene or proteindelivery device comprises an epicardial patch including the polymermatrix.
 28. The system of claim 1, wherein the nucleic acid or proteinis released at a rate controlled by the strength of the electric field.29. The system of claim 1, wherein the implantable pulse generatorfurther comprises a pacing circuit coupled to the implant controller,and wherein the implant controller includes a pacing control moduleadapted to control a delivery of pacing pulses in conjunction with therelease of the nucleic acid or protein.
 30. The system of claim 29,further comprising at least one atrial pacing lead coupled to the pacingcircuit to deliver atrial pacing pulses.
 31. The system of claim 29,further comprising at least one ventricular pacing lead coupled to thepacing circuit to deliver ventricular pacing pulses.
 32. The system ofclaim 29, wherein the implantable pulse generator further comprises acardiac resynchronization therapy (CRT) circuit coupled to the implantcontroller, and wherein the implant controller includes a CRT controlmodule adapted to control a delivery of CRT in conjunction with therelease of the nucleic acid or protein.
 33. The system of claim 29,wherein the implantable pulse generator further comprises a remodelingcontrol therapy (RCT) circuit coupled to the implant controller, andwherein the implant controller includes an RCT therapy control moduleadapted to control a delivery of RCT therapy in conjunction with therelease of the nucleic acid or protein.
 34. The system of claim 29,wherein the implantable pulse generator further comprises defibrillationcircuit coupled to the implant controller, and wherein the implantcontroller includes a defibrillation control module adapted to control adelivery of defibrillation shocks in conjunction the release of thenucleic acid or protein.
 35. The system of claim 34, further comprisingat least one atrial defibrillation lead coupled to the defibrillationcircuit to deliver the defibrillation shocks to one or more atria, andwherein the defibrillation control module comprises an atrialdefibrillation control module.
 36. The system of claim 34, furthercomprising at least one ventricular defibrillation lead coupled to thedefibrillation circuit to deliver the defibrillation shocks to one ormore ventricles, and wherein the defibrillation control module comprisesa ventricular defibrillation control module.
 37. The system of claim 1,further comprising an external system communicatively coupled to theimplantable pulse generator, the external system including: apresentation device to present one or more of the sensed physiologicalsignal and the detected predetermined cardiac condition; a user inputdevice to receive the external command; and an external telemetry moduleto transmit the external command to the implant telemetry module. 38.The system of claim 37, wherein the external system comprises aprogrammer.
 39. The system of claim 38, wherein the external systemcomprises an advanced patient management system including: an externaldevice wirelessly coupled to the implantable pulse generator viatelemetry; a remote device to provide for access to the implantablepulse generator from a distant location; and a network connecting theexternal device and the remote device.
 40. The system of claim 39,wherein the external device comprises the user input.
 41. The system ofclaim 39, wherein the remote device comprises the user input.
 42. Thesystem of claim 1, wherein the polymer matrix comprises a syntheticnonbiodegradable polymer.
 43. The system of claim 1, wherein theimplantable gene or protein delivery device comprises an implantableiontophoresis gene or protein delivery device, and the nucleic acid orprotein contained in the polymer matrix is released from the implantablegene or protein delivery device by iontophoresis.
 44. A method foroperating an implantable gene or protein delivery system coupled to animplantable device, comprising: sensing a physiological signalindicative of a predetermined cardiac condition using an implantablesensor; detecting the predetermined cardiac condition from thephysiological signal; receiving an external command transmitted to theimplantable device from an external system; producing an electricalsignal in response to the predetermined cardiac condition and theexternal command using the implantable device; transmitting theelectrical signal from the implantable device to an implantable gene orprotein delivery device through an implantable lead system; creating anelectric field using the electrical signal; and applying the createdelectric field to a polymer matrix of the implantable gene or proteindelivery device, the polymer matrix containing isolated nucleic acidwhich encodes at least one gene product or binds at least one selectedmRNA or isolated protein, wherein the created electrical field iseffective to release the nucleic acid or protein from the polymer matrixvia iontophoresis.
 45. The method of claim 44, wherein the nucleic acidor protein is released at a rate controlled by the strength of theelectric field.
 46. The method of claim 44, wherein sensing thephysiological signal comprises sensing at least one electrogram, anddetecting the predetermined cardiac condition comprises detecting anarrhythmia.
 47. The method of claim 46, wherein detecting thepredetermined cardiac condition comprises detecting an atrialfibrillation.
 48. The method of claim 46, wherein detecting thepredetermined cardiac condition comprises detecting a ventricularfibrillation.
 49. The method of claim 44, wherein sensing thephysiological signal comprises sensing an physiological signalindicative of ischemia, and detecting the predetermined cardiaccondition comprises detecting an ischemia.
 50. The method of claim 44,wherein sensing the physiological signal comprises sensing a signalindicative of a cardiac metabolic level.
 51. The method of claim 50,wherein sensing the signal indicative of the cardiac metabolic levelcomprises sensing at least one of a pH value, an oxygen pressure (PO2),a carbon dioxide pressure (PCO2), a glucose level, a creatine level, aC-creative protein level, a creatine kinase level, and a creatinekinase-MB level.
 52. The method of claim 44, wherein sensing thephysiological signal comprises sensing tissue impedance.
 53. The methodof claim 52, wherein sensing the tissue impedance comprises sensingpulmonary impedance.
 54. The method of claim 52, wherein sensing thetissue impedance comprises sensing an impedance indicative of minuteventilation.
 55. The method of claim 44, wherein sensing thephysiological signal comprises sensing a pressure in a cardiovascularsystem.
 56. The method of claim 55, wherein sensing the pressurecomprises sensing at least one of a left atrial pressure, a leftventricular pressure, an arterial pressure, and a pulmonary arterialpressure.
 57. The method of claim 55, wherein detecting thepredetermined cardiac condition comprises detecting a systolicdysfunction.
 58. The method of claim 55, wherein detecting thepredetermined cardiac condition comprises detecting a diastolicdysfunction.
 59. The method of claim 44, wherein sensing thephysiological signal comprises sensing a stroke volume.
 60. The methodof claim 44, wherein sensing the physiological signal comprises sensinga neural activity.
 61. The method of claim 60, wherein sensing theneural activity comprises sensing a neurohormone level.
 62. The methodof claim 60, wherein sensing the neural activity comprises sensingneural electrical activities.
 63. The method of claim 62, whereinsensing the physiological signal comprises detecting a heart ratevariability.
 64. The method of claim 44, wherein sensing thephysiological signal comprises sensing a renal function.
 65. The methodof claim 64, wherein sensing the renal function comprises sensing atleast one of a renal output, a filtration rate, and an angiotensin IIlevel.
 66. The method of claim 44, wherein sensing the physiologicalsignal comprises sensing at least one of heart sounds and respiratorysounds.
 67. The method of claim 66, wherein detecting the predeterminedcardiac condition comprises detecting a predetermined cardiac conditionwhen third hear sound (S3) amplitude exceeds a predetermined threshold.68. The method of claim 44, wherein sensing the physiological signalcomprises sensing a signal indicative of a degree of myocardialremodeling.
 69. The method of claim 68, wherein sensing the signalindicative of the degree of myocardial remodeling comprises sensing asize of an injured myocardial region.
 70. The method of claim 44,further comprising delivering pacing pulses in conjunction withreleasing the nucleic acid or protein.
 71. The method of claim 70,further comprising delivering a cardiac resynchronization therapy (CRT)in conjunction with releasing the nucleic acid or protein.
 72. Themethod of claim 70, further comprising delivering a remodeling controltherapy (RCT) in conjunction with releasing the nucleic acid or protein.73. The method of claim 70, further comprising deliveringcardioversion/defibrillation shocks in conjunction with releasing thenucleic acid or protein.
 74. The method of claim 73, wherein deliveringthe cardioversion/defibrillation shocks comprises delivering atrialdefibrillation shocks.
 75. The method of claim 73, wherein deliveringthe cardioversion/defibrillation shocks comprises delivering ventriculardefibrillation shocks.
 76. The method of claim 44, further comprising:transmitting one or more of the sensed physiological signal and adetection of the predetermined cardiac condition to the external system;and presenting the one or more of the sensed physiological signal and adetection of the predetermined cardiac condition through the externalsystem.
 77. The method of claim 44, wherein receiving the externalcommand comprises receiving the external command entered by a physicianor other caregiver through the external system.
 78. The method of claim44, wherein receiving the external command comprises receiving theexternal command entered by a patient through the external system. 79.The method of claim 44, wherein producing the electrical signalcomprises producing an electrical signal that creates an electric fieldcapable of releasing the nucleic acid or protein from the polymer matrixby iontophoresis.
 80. A method to transiently deliver isolated nucleicacid which encodes at least one gene product or binds at least oneselected mRNA, or isolated protein to a mammal being at risk of apredetermined cardiac condition, comprising: programming the timing ofthe electric signal produced from the system of claim 1 implanted in themammal at risk of the predetermined condition, in response to detectionof the condition so as to transiently deliver the nucleic acid orprotein via iontophoresis in an amount effective to inhibit or treat thecondition or at least one symptom thereof.
 81. The method of claim 80,wherein the system is in or on the heart of the mammal.
 82. The methodof claim 80, wherein the system is in or on a blood vessel of themammal.
 83. The method of claim 80, wherein the condition is atrialfibrillation, heart failure, ventricular fibrillation, ischemia,brachycardia or hyperplasia.
 84. The method of claim 80, wherein thenucleic acid or protein is delivered to at least one of the atria. 85.The method of claim 80, wherein the nucleic acid or protein is deliveredto at least one of the ventricles.
 86. The method of claim 80, whereinthe nucleic acid or protein delivered is a connexin nucleic acid orprotein.
 87. The method of claim 80, wherein the nucleic acid or proteindelivered is an atrial-specific ion channel gene or protein.
 88. Themethod of claim 87, wherein the nucleic acid or protein delivered isassociated with I_(f).
 89. The method of claim 80, wherein the nucleicacid or protein delivered is a non- specific ion channel gene orprotein.
 90. The method of claim 89, wherein the nucleic acid or proteindelivered is associated with I_(K1), I_(CaL), I_(to), I_(Kr), I_(Kur),I_(KATP), I_(Na) or I_(Na/Ca).
 91. The method of claim 80, wherein thegene product or protein regulates gap junctions.
 92. The method of claim80, wherein the gene product or protein alters conduction in themyocardium.
 93. The method of claim 80, wherein the protein is or thenucleic acid encodes a regulatory protein that blocks ion channels,upregulates ion channels, downregulates ion channels, or alters ionchannel kinetics.
 94. A system, comprising: an implantable pulsegenerator including: a sensor to sense a physiological signal indicativeof a predetermined cardiac condition; an event detector, coupled to thesensor, to detect the predetermined cardiac condition from thephysiological signal; and an implant controller coupled to the eventdetector, the implant controller including a gene or protein deliverycontrol module configured to produce an electrical signal to controliontophoretic gene or protein delivery in response to the predeterminedcardiac condition; and an implantable gene or protein delivery devicecoupled to the implantable pulse generator, the implantable gene orprotein delivery device including an epicardial patch comprising apolymer matrix and isolated nucleic acid which encodes at least one geneproduct or binds at least one selected mRNA, or isolated protein, thenucleic acid or protein contained in the polymer matrix and releasedfrom the implantable gene or protein delivery device in response to anelectric field applied to the polymer matrix, the electric field createdby the electrical signal.